Analysis system employing a plural chamber cuvette structure

ABSTRACT

An analysis system includes a plural chamber cuvette assembly that holds chemical materials and is adapted to receive an unknown to be analyzed in one of the chambers, a record that specifies information as to the nature of the stored chemical material and the type of analysis to be performed, and photometric instrumentation for performing a chemical analysis that responds to the material in the sample chamber in the cuvette assembly and the record. The instrument is automatically calibrated in response to information specified by the record and an analysis is performed automatically merely in response to the operation of a single control.

United States Patent Rosse et al.

1451 Nov. 21, 1972 [54] ANALYSIS SYSTEM EMPLOYING A PLURAL CHAMBERCUVETTE STRUCTURE Instrumentation Laboratory, Inc., Lexington, Mass.

Filed: June 12, 1970 Appl. No.: 45,758

US. Cl ..356/39, 23/253 R, 250/218, 356/205 356/246 1m. 01. ..G01 n21/24 Field ofSearch ..23/253; 250/106 so, 218, 250/219 DC; 235/151.35,61.6 H; 356/246, 39,40,1s0,2 05

[56] References Cited UNITED STATES PATENTS v3 ,437,822 4/1969 Fitzsimmons ..35 6/ 205 3,523,737 8/1970 Wood et al. ..356/246 3,562,5012/1971 Mears ..235/l51.35 3,571,596 3/1971 Frank et al ..250/l06 SCPrimary Examiner-Ronald L. Wibert Assistant Examiner-Orville B. Chew, llAttorney-Willis M. Ertman [5 7] ABSTRACT An analysis system includes aplural chamber cuvette assembly that holds chemical materials and isadapted to receive an unknown to be analyzed in one of the chambers, arecord that specifies information as to the nature of the storedchemical material and the type of analysis to be performed, andphotometric instrumentatiQn for performing a chemical analysis that p stoth; mateniinthesample, chamber'in the cuvette assembly and the record.The instrument is automatically calibrated in response to informationspecified by the record and an analysis is performed automaticallymerely in response to the operation of a single control.

29 Cla i| 1 1 s 11 Drawingfigures SHEET 1 BF 5 FIGI PATENTEDnnvm m2PATENTEOnnm I972 SHEEI 3 [IF 5 PATENTEU NOV 21 1912 mom um x SHEET 0F 5ANALYSIS SYSTEM EMPLOYING A PLURAL CHAMBER CUVETTE STRUCTURE SUMMARY OFINVENTION This invention relates to analysis systems.

A need exists for instrumentation that produces accurate chemicalanalysis data and which can be operated by untrained personnel. Su chinstrumentation wouldassist laboratories in contending with the shortageof skilled personnel and as such should minimize the number ofoperations required, eliminate the need for calculations, and presentthe analysis results directly, accurately and unambiguously. Chemicalanalyses may be perfonned in a variety of manners. In photometricanalyses, for example, measurements may be made directly, by comparisonwith a standard, or as a function of the rate of chemical change. Suchtechniques are frequently employed in the analysis of blood or otherbody fluids. Frequently as part of a diagnostic procedure, a chemicalanalysis of a sample of such fluidfor enzymes, hemoglobin, chloresterol,glucose etc. provides useful diagnostic information. While laboratoryservices for performing such analyses are available, the use of suchservices often entails a delay of several days ormore before analysisinformation is available.

It is an object of this invention to provide a novel and improvedanalysis system which facilitates operation of analysis instrumentationby untrained personnel.

Another object of the invention is to provide a novel and improvedinstrumentation for use with prepackaged chemical materials whichenables such materials to be stored in a reliable manner, and to easilybe used in obtaining analysis information.

A further object of this invention is to provide novel and improvedanalysis instrumentation.

Another object of the invention is to provide novel and improvedchemical analysis instrumentation particularly adapted for use in theanalysis of blood samples;

A further object of the invention is to provide a novel and improvedanalysis system which enables the performance of complex blood chemicalanalytical procedures with the minimum of trained technique whileobtaining data sufficiently accurate for diagnostic purposes.

Another object of the invention is to provide a novel and improvedanalysis system which can be used for a wide variety of blood chemistrytests.

In accordance with the invention there is provided an analysis systemwhich includes a container for storing a chemical material and havingmeans for introducing a material to be analyzed into the container formixing with the stored chemical material. Associated with the containeris a record that specifies information as to the nature of the storedchemical material and the type of analysis to be performed.Instrumentation for performing the analysis includes means for receivingthe container to process the mixture of materials stored therein, andmeans responsive to information on the record for setting components ofthe instrumentation to perform an analysis as a function of acharacteristic of the chemical material as specified by the record.

In a preferred analysis system the instrumentation includes a radiationsource and a detector in spaced relation defining an optical path. Meansare provided for positioning a plural chamber cuvette assembly in theoptical 'path. The system further includes circuitry for modifying theoutput signal produced by the detector from the material in one samplechamber as a function of the output signal produced by the detector fromthe material in another sample chamber and providing a signal indicativeof a parameter of the material in the first sample chamber. In aparticular embodiment, the cuvette assembly includes three samplechambers for holding an unknown blood sample to be analyzed, a standardmaterial, and a blank material. The circuitry generates three absorptionsignals A A and A and from these signals generates two differencesignals (A A S-A and a signal that is a function of the ratio of thosetwo difference signals.

While the sample chambers may be sensed simultaneously or sequentially,in a preferred embodiment a single optical path is established and thechambers are moved into that optical path sequentially. In thatembodiment the modifying circuitry includes a first storage circuit forholding a signal representative of the blank material, a second storagecircuit for holding a signal representative of the standard material,and circuitry for generating the modified signal as .a function of thestored signals.

Other objects, features andadvantages of the invention will be seen asthe following description of a particular embodiment progresses, inconjunction with the drawings, in which: v

FIG. 1 is a perspective view' of "components of a biochemical analysissystem constructed in accordance with the invention;

FIG. 2 is a side view, with parts broken away, of the cuvette assemblyshown in FIG. 1;

FIG. 3 is a sectional view of the cuvette assembly taken along the line3--3 of FIG. 2;

FIG. 4 is a sectional view of the cuvette assembly taken along the line4--4 of FIG. 2;

FIG. 5 is a top plan diagrammatic view of the cuvette assembly and anincubator unit of the apparatus shown in FIG. 1;

FIG. 6 is a diagrammatic sectional view taken along the line 6-6 of FIG.5;

FIG. 7 is a block diagram of the photometric system of the apparatusshown in FIG. 1;

FIG. 8 is a schematic diagram of the log converter circuitry indicatedin block 134 in FIG. 7;

FIG. 9 is a schematic diagram of other components of the electricalcircuitry shown in block form in FIG.

FIG. 10 is a logic diagram of the logic indicated by block 162 in FIG.7; and I FIG. 11 is a diagrammatic view of the sensor 164 that controlsand indicates the position of the cuvette shuttle.

DESCRIPTION OF PARTICULAR EMBODIMENT With reference to FIG. 1 there isshown a biochemi- I cal analysis instrument that includes a housing 10on which is mounted a dispensing unit 12 having two dispensing channels14-1 and 14-2. To the right of the dispensing unit 12 is an incubatorsection 16 that includes incubator chambers 18-1 18-8. At the top ofeach incubator chamber is an interlock slot 20 and above each chamber isan indicator light 22. A

photometer section 24 is disposed above the incubator section 16 andincludes a slot 26 for receiving a cuvette assembly 40; acard readerunit 28', a digital display 30; a units display 32; a start button 34and an alarm lamp 36. Used with this instrument is a disposable cuvetteassembly 40 and a correlated card 42 which includes a data section 44having calibrating and control information and an instruction section46. in a typical system, a kit of 20 cuvette assemblies 40, a supply ofa standard (if necessary) for use with the cuvette assemblies 40 and acontrol card 42 having coded calibrating and control informationcorrelated with the standard material and the analysis to be performedis supplied for use with the instrument. A different kit is provided foreach type of analysis.

The cuvette assembly 40, as shown in FIGS. 2-4, is formed of twocomponents, a top 48 and a body portion 50, both formed ofsuitablematerial such as glass, or a polymeric material such as apolyolefin, a polycarbonate, or an acrylic. A preferred material is atransparent TPX methylpentene polyolefin material that has an absorptionof approximately 0.125 optical density at a wavelength of 3,400Angstroms; a vicat softening point of 179C; and excellent chemicalresistance properties.

The body 50 has two side walls 52, 54, each 0.050 inch thick, that taperoutwardly from bottom to top at an angle of about 1. Side walls 52, 54are joined together at their bottom by base wall 56. As indicated inFIGS. 2 and 3, three sample chambers 60-1, 60-2 and 60-3 and a handlechamber 62 are formed in the cuvette assembly. These chambers aredefined by lateral separator wall members 64 that have a thickness attheir upper ends of about 0.040 inch. Each sample chamber 60 has atransverse width between side walls 52, 54 of about three-eighths inchand a lateral width of about inch. The height of the cuvette assembly is1% inches and its length is 4 inches. instruction and/or labelinginformation may be secured to one or both inner surfaces of the handlechamber 62. Formed in the outer surface of each side wall of the threesample chambers 60 is an optical surface 70 of about nine-sixteenthsinch in height and having a surface finish in the order of micro-inches.Each surface is recessed about 0.005 inch to provide a protective zone.in the optical area defined by surface 70, the side wall thickness ineach chamber 60 is maintained within a tolerance of 0.0004 inch of themean wall thickness of the three chambers. The optical path lengths ofthe three chambers thus are identical within close tolerances.

The cover member 48 has a downwardly projecting ridge 72 which engagesthe upper surface of the body 50 and, after chemical material has beenintroduced into one or more of the chambers 60, a hermetic seal of thechambers 60 and 62 is provided as by ultrasonic welding. 1n the upperwall of each chamber is formed a frangible section 74 of reducedthickness which may be broken away to permit introduction of materialssuch as a reconstituting agent or the unknown to beanalyzed into thesample chambers 60. An interlock key 76, divided into two sections 76-1and 76-2, projects from the upper surface of the cover member 48. Eithersection 76-] or 76-2 may be omitted thus varying the codmg.

As shown in FIGS. 5 and 6, each incubator chamber 18 is of cast aluminumand is disposed behind an aperture in the front wall 80 of theinstrument. Immediately behind wall 80 is-a thermal insulator member 82which provides thermal isolation between areas outside the instrumentand the incubator resistance heater rod elements 84, 86. Four. of theincubator chambers (18-1 18-4) have thermistor controlled heaters set at37C and controlled to maintain temperature within 03C and the other fourincubator chambers (18-5 18-8) have thermistor controlled heaters set at100C and controlled to maintain temperature within 1C. A light source isassociated with each pair of incubator chambers 18 and four transmittingfiber optic channels 92, two in each direction, extend from light source90 with their remote ends supported in the corresponding insulatormember 82. A corresponding aligned pair of receiving fiber opticchannels 94 are secured in the opposed insulator member and are coupledvia photodiodes 96 to timing and control logic 98 which provides threedifferent timing-intervals and inturn operates indicator lamp 22 and anaudible buzzer'(not shown). Normally light from lamp 90 is fed viatransmitting fiber optic channels 92 to'the receiving fiber opticchannels 94 for sensing by photosensors 96. When a cuvette assembly 40is inserted in a proper incubator chamber 18, the location of projection76 on the left or right side of assembly 40 being keyed to the positionof interlock slot 20, one or both sections 76-1, 76-2 (depending on thecoding) block the transmission of light to sensors 96 and operate timinglogic 98 to initiate a timing cycle. With this coding three differenttiming cycles may be initiated, and it will be obvious that otheradditional timing cycles may be obtained by varying the nature of thecoded control tab 76. At the end of the timing cycle selected, logic 98produces an output that energizes lamp 22 and the buzzer to indicate tothe operator that the cuvette assembly 40 in that incubator chamber isready for photometric analy- SIS.

A block diagram of the photometric section of the instrument is shown inFIG. 7. That section includes a shuttle 100 (disposed behind port 26)which receives and secures the cuvette assembly 40 in a predeterminedlocation and which is driven via shuttle drive linkage by a motor 102.The shuttle drive sequentially positions the three chambers 60 in anoptical path 104 that extends from a twenty watt quartz iodine radiationsource 106 through filter wheel 108 to photodiode radiation sensor 110.The filter wheel 108 is in the form of a disc and has sixcircumferentially disposed filter elements and is rotated by a motor112. The position of the filter disc is sensed by cooperation of slotsin the filter disc and a plurality of photoelectric light sensors andlogic (diagrammatically indicated at 114) which provide a binary codedoutput signal to compare circuit 116.

The card reader 28 which senses the data portion 44 of card 42 has alight source 118 and light distributing system 120 that has 50 outputchannels 122 arranged in 5 X 10 matrix. A check channel is also providedto verify the proper positioning of the card in the reader. Each sensorchannel of the card reader includes a light sensor 126, and one or moreof the light sensors are coupled to translating logic 128 which appliescontrol signals over output lines 130. The signals on line 130-1 areapplied to control the operation of dispenser 12; the signals on outputline 130-2 are applied as an input to comparison logic 116', the signalson output lines 130-3 8 are applied to control the signal processingcircuitry that responds to material in the cuvette chambers; and theoutput signal on line 130-9 is applied to the decimal display unit. Thedata on the card identifies the particular test and has dispensinginformation and calibration information as a function of the particulartest and the chemicals supplied for performing the test. For example,output channel 130-2 applies a signal to compare circuit 116 and thatsignal applies an output over line 132 to control the filter wheel drivemotor 112. Thus, in response to test mode information stored on the card42 that is correlated with a particular cuvette assembly 40, oninsertion of that card into the card reader, the compare circuit 116provides an output on line 132 to energize motor 112 and rotate filterwheel 108 until the proper filter element is positioned in the opticalpath 104. Motor 112 is then de-energized.

The output of radiation sensor 110 is applied to a log converter circuit134 which provides an output as a logarithmic function of the inputsignal from photodiode 110. Connected in circuit with the log converterarrangement is a switch 136 and a hold circuit 138. The output of thelog converter circuit is applied through a first input of switch 140 toa digital voltmeter 142; along a second path through differentiator 144,filter network 146 and absolute value amplifier 148 to a second input ofswitch 140; and along a third path through a first input of switch 150,scaling amplifier 152, switch 154 and storage circuit 156. The output ofstorage circuit 156 is applied to the reference input of the digitalvoltmeter 142 and to error logic 158 which has an output that energizeserror indicator or alarm lamp 36 when the output of the hold circuit 156deviates from preestablished limits as specified by data from the cardreader supplied on output line 130-8. Switch 150 has a second input froma precision voltage source 160. The circuitry also includes controllogic 162 which responds to inputs from sensor 164 that provides anindication for position of the cuvette shuttle 100; inputs from the cardreader over output lines 130- 3; and inputs from start button 34. Thelogic has outputs over line 170 to control switch 136, over line 172 tocontrol a switch in filter network 146, over line 174 to control switch154, over line 176 to the digital voltmeter 142 and the error logic 158in a strobing operation, and on line 178 to control the shuttle drivemotor 102.

A schematic diagram of the log converter circuit 134, switch 136 andstorage circuit 138 is shown in FIG. 8. Terminal 180 receives a signalfrom photodiode 110 which in this embodiment is a TS 433 photodiode;terminal 182 receives a signal from logic circuit 162 on line 170 andterminals 184 receive signals from the card reader over lines 130-4. Thesignal applied at input 180 is applied through resistor 186 to the inputof forward amplifier stage 188. The output of stage 188 is applied overoutput line 190 to differentiator 144, over line 192 to switch 150, andthrough resistor 194 to switch 136. Log converter transistor 196 isconnected in the feedback path around forward amplifier 188 and incircuit with a digitally programmed voltage divider 198 and referencetransistor 200. Transistor 200 is in 1 the feedback loop of referencecurrent source amplifier fier 188 and reference current source amplifier202.

The digitally programmed voltage divider 198 includes switch units 210,each of which is connected in series with a corresponding resistor211-217. The network of resistors 211-214 may be either connected inseries or grounded to provide a first voltage divider network thatdefines a digit value, and resistors 215-217 may be selectivelyconnected in circuit to provide a multiplier effect, this circuitryproviding allowing selection of the volts per decade response of thesystem over a range of values from one volt per decade to 1,500 voltsper decade. Additional information concerning this circuitry may be hadwith reference to copending application Ser. No. 45,705 now US. Pat. No.3,659,082 entitled ELECTRICAL CIRCUITRY and filed concurrently herewithin the name of Norman F.F.J. Rolfe and assigned to the same assignee asthis application.

Additional details concerning other components of the electricalcircuitry may be had withreference to FIG. 9'. As shown in that Figure,the output from the log converter 134 at terminal 180 is applied througha differentiator circuit 144 which includes capacitor 220 and resistor222. A filter network 146 includes three filter stages, a first stageincluding a low input current operational amplifier diagrammaticallyindicated at 224 across which is connected a capacitor 226, resistor 228and switch 230 that is, operated in response to a signal on line 172applied at terminal 232; the second stage includes low pass filterhaving resistors 234 and 236 and capacitor 238; and a third stagesimilar to the first stage includes operational amplifier 240, capacitor242 and resistor 244. The output of the filter network 146 is applied toan absolute value amplifier stage 148 that includes two operationalamplifier circuits 246, 248 arranged so that the output at line 250 isalways positive. The signal on line 250 is applied to switch network andspecifically to the FET switch 252 for application to input 254 of thedigital voltmeter 142. A second FET switch 256 is connected in circuitbetween terminal 180 and input 254. Switch network 140 is operated inresponse to a signal from the card reader over line 130-7 applied atterminal 258.

A signal from terminal 180 is also applied to switch network whichincludes field effect transistors 260 and 262, the switch network beingoperated in response to a signal from the card reader over lines 130-5applied at terminal 264 to either connect terminal 180 or precisionvoltage source to the scaling amplifier 152. That amplifier includes alow input current operational amplifier stage that includes two fieldeffect transistors 268, 270 and operational amplifier 272. Connectedacross the operational amplifier is a multiply network that includesresistors 274, 276 and 278, resistor 276 being connected in circuit byswitch 280 in response to a signal from the card reader over line 130-6applied at terminal 282 and resistor 278 being connected in circuit byswitch 284 in response to a similar signal over line 130-6 applied atterminal 286. Connected between the output of operational amplifiercircuit 272 and switch 154 is a twelve stage digit network that includesresistors 290, each of which is connect ed in circuit by a switch 292 inresponse to a signal from the card reader over line 130-6 applied atterminal 294. Switch 154 includes a field effect transistor 296 andoperates in response to a signal from-logic circuit 162 over line 174applied at terminal 298. The storage circuit 156 includes a similaramplifier stage that includes two field effect transistors 300, 302, anoperational amplifier 304 and a storage capacitor 306. Output transistor308 has voltage limiting zenar diode 310 connected across it and thecircuit output is applied to the reference input 312 of the digitalvoltmeter. A signal is also applied on line 314 to the error checkcircuit 158.

The logic circuit 162, shown in FIG. 10 operates in response to signalsfrom the cuvette drive sensor 164. That sensor, as shown in FIG. 11,includes a mask member 320 which is driven in rotation by motor 102 andhas three slots 322, 324, and 326 that provide, respectively, X, Y, andZ signals. When the motor drive 102 is in the rest position light passesthrough slot Z. When the motor is energized, the drive is rotated toadvance mask disc 320 to a first measurement position (X, Y) while thecuvette 40 is not interposed in light path 104 (position 1). The motoris driven continuously and at point 328 (shortly after the condition X,Y has been established) the cam on the drive advances the shuttle toposition the firstsample chamber 60-1 in the light path 104. At point330 (in the XY condition) the shuttle is advanced to position the middlesample chamber 60-2 in the light path; and at point 332 (in the (Ycondition) the drive advances the shuttle to position the third chamber60-3 in the light path. At point 334 the shuttle is returned to itsinitial position and when the Z slot 326 is reached the motor 102 isturned off. The X light sensor applies a signal at terminal 340, the Ylight sensor applies a signal at terminal 342 and the Z light sensorapplies a signal at terminal 344. Each X and Y signal is applied throughan inverter 346 to generate X and X signals and Y and Y signals asindicated and those signals apply in coding logic that in- I eludes ANDcircuits 350 to generate control outputs, the output on line 352indicating the control di'sc 320 is in position 1, the output on line354 that disc 320 is in position 2, the output on line 356 that disc 320is in position 3 and the output on line 358 that disc 320 is in position4. The output on line 354 is also applied on line 416 to reset the errorsignal circuit. I

lnfonnation is also supplied to the logic circuit from the card reader,rate-static mode information being supplied on line 360 and othercontrol information on line 362. A group of four AND circuits 364, 366,368 and 370, together with inverter 371 respond to signals on lines 354,356 and 362. AND circuit 364 has an output in response to inputs onlines 354 and 362; AND circuit 366 has an output in response to an inputin line 354 and the absence of a signal on line 362; AND circuit 368 hasan output in response to input on line 356 and the absence of signal online 362; and AND circuit 370 has an output in response to signals onlines 356 and 362. i

The input over lines 130-3 from the card reader on appears on line 360and provides rate and mode information, the presence of the signal online 360 indicat- 358 and still another input from inverter 382. Therate modesignal on line 374 is applied to AND circuit 384 which has asecond input from line 358, to AND circuit 386 which has a second inputfrom OR circuit 388 and to OR circuit 412. The output of AND circuit 384is applied to timer 390 (a four stage device that counts from zero to 15in response to signals passed by AND circuit 392 from clock signals atfour second intervals at terminal 394). The signal from the Z sensor atterminal 344 is applied through amplifying circuitry 396 and an inverter398 to OR circuit 400 which has a second input from start switch 34 online 166 and its output is applied to motor control circuit 402 whichcontrols the shuttle drive motor 102. Subsidiary controls responsive totimer outputs are'applied to this circuit from the AND circuits 380,404. Timer outputs are also applied through OR circuit 388 and inverter406 to OR circuit 408 which has a second input from the timer output(0010) and produces an. output on line 172 to reset the filter networkand start a rate measurement that continues through time (1 1 10). ORcircuit 4l0has a first input from AND circuit 378 and a second inputfrom the timer output (1110) and an output on line 176 which strobes thedigital voltmeter 142 and the error check circuit 158. OR circuit 412has an output on line 174 to operate the switch 154 in response to arate mode signal on line 374 or a signal from either AND circuit 366 or370. OR circuit 414 provides an'output on line 170 to cause the zeroingoperation of the log amplifier and has inputs from line 352 and from ANDcircuits 364, 368 and 386.

A variety of biochemical analyses may be performed with this apparatus.The following table indicates typical examples of the types oftests thatmay be made with this apparatus:

normal time range minutes 60-100 20 i incubation temperature C units mg/100 ml Bessey-Lowry mg/100 ml 100C 8-18 505 g/l 00 ml 37C 10-23 525g/100 ml 37C 6-8 640 rug/100 ml 37C -250 incubation i For each test, akit of correlated material is supplied,

a typical kit including a set of 20 cuvettes 40, a supply of a standardfor use with the 20 cuvettes and calibrating data card 42 which containscontrol data for the particular test including data on the standard. Thecomponents of the kit are related, as by color coding to facilitateoperator handling.

This instrument as controlled by a card 42 and card reader 28 isoperable in the following three modes:

Standard R (A AB)/(A A,,) X K Absolute R (A A,,) X K Rate R =dAx/dt X KAn illustrative example of each mode follows. Determination of serumglucose uses the standard mode. All three cuvette chambers 60-1 60-3contain four milliliters of liquid reagent (6 percent orthotoluidine inglacial acetic acid) when the cuvette is received by the user. Under thecontrol of card reader 28 and the corresponding glucose data card 42,the card reader has an output over channel 130-1 to control dispenser 12and load dispenser channel 14-1 with one hundred microliters with aglucose serum standard (containing a precisely predetermined 200milligrams per 100 milliliters, and that is coordinated withtheglucose'data card 42) and channel 14-2 is loaded with 100 microliters ofa sample of the serum to be analyzed (typically that of a patient). Acuvette is then positioned so that chamber 60-2 and 60-3 are alignedwith channels 14-1 and 14-2, respectively, and these volumes aredischarged into those chambers. Nothing is added to chamber 60-1. Afterthe chambers have been resealed and the contents mixed by inversion, thecuvette assembly 40 is placed in one of the 100C incubator units 18-518-8 and incubated for 20 minutes.

When the incubation period is complete, the lamp 22 above that chamberlights (and an audible alarm is sounded). With the glucose data card 42in the card reader 28, the card causes motor 112 to stop the filterwheel 108 so that the 6400 Angstrom filter is disposed in the opticalpath 104 between the lamp 106 and photodiode 110 by an output signalover line 130-2. Gain factors are adjusted in the log converter circuit134 by an output over line 130-4 and in the scaling amplifier 152 by anoutput over line 130-6. The card reader also closes switch 150 so thatthe output from the log converter circuit 134 is applied directlythrough switch 150 to the scaling amplifier 152, and energizes anappropriate decimal point, and the appropriate units display 32.Depression of the start button 34 applies a signal over line 166 tologic 162 which in turn generates a control signal over line 178 toenergize the shuttle drive motor 102.

Initially the cuvette assembly is in the position shown in H6. 7(position 1). The shuttle drive advances the cuvette assembly toposition 2 so that chamber 60-1 is positioned in the optical path 104.During these intervals, the shuttle position sensor 164 indicates to thelogic circuitry 162 the position of the cuvette and during theseintervals, the logic circuitry 162 produces an output over line 170 toclose the switch 136 in the log converter feedback path, applying theoutput signal from the log converter through switch 136 and storagecircuit 138 as a feedback to the log converter circuit 134 in a zeroingoperation. Since chamber 60-1 contains only the blank solution (noglucose standard or unknown was added to this chamber).the intensity of.

light striking the photosensor 110 and its output current correspondsphotometrically to the zero concentration of glucose. The log convertercircuit 134 has this current applied to it and produces an outputvoltage equal to the log of the input current. This output signal is fedback through switch 136 and storage circuit 138 as a reference currentto the log converter circuit. Switch 136 is then opened and the storagecircuit 138 holds this voltage and continues to apply a referencecurrent to the log converter that is proportional to the negativeintensity of the blank solution.

The shuttle mechanism, after an interval of about two seconds inposition 2, advances the cuvette to position 3 so that standard chamber60-2 is positioned in the optical path 104. This action is sensed bysensor 164 and applies a signal to logic circuitry 162 to produce anoutput signal on line 174 to close switch 154. The gain of the scalingamplifier 152 has been set from signals from the card reader over line130-6 to calibrate the scaling ampli er as a fiinction of the standardglucose solution sup lied with the card. During that interval that thestandard in chamber 60-2 is in path 104, the current generated by sensorcauses the log converter 134 to produce an output voltage proportionalto log of the absorbance of the standard minus the absorbance of theblank (A -A After amplification in accordance with the calibratinginformation from the card reader, this signal is stored as'a voltage instorage circuit 156 and applied to the reference voltage input of thedigital voltmeter 142.

The shuttle mechanism, again after interval of about two seconds,advances the cuvette so that the third (unknown) chamber 60-3 ispositioned in the optical path 104. Sensor 164 produces a position fouroutput signal to the logic circuitry 162 and that circuitry removes theoutput signal on line 174 so that switch 154 is opened. The output fromthe log converter 134 is applied through switch 140 to the analogvoltage input of the digital voltmeter 142. This output with the chamber60-3 in the optical path 104, is proportional to the log of eA -A (theabsorbance of the unknown minus the absorbance of the blank). The outputof the digital voltmeter applied to display 30 in response to thestrobing signal on line 176 is:

x AB)/(AS AB) X K The number displayed is directly proportional to theconcentration of glucose in the unknown serum and the units display 32indicates that this number is displayed in units of milligrams per 100milliliters.

Determination of hemoglobin by the Cyanmethemoglobin procedure employsthe absolute mode. In this measurement, chamber 60-1 is empty and isunused in the analysis sequence, and each of chambers 60-2 and 60-3 assupplied in the kit has four milliliters of a reagent. A potassiumcyanide tablet is inserted into each chamber 60-2 and 60-3 by thetechnician to complete the reagent and the dispenser 12 is controlled byoutput -1 of card reader 28 to load 50 microliters of the patients bloodinto dispenser channel 14-2. The dispenser is then operated to discharge50 microliter sample of whole blood into cuvette chamber 60-3. Thecontents of the cuvette assembly,

after the chambers are sealed, are mixed by inversion and the cuvette isincubated in a 37C unit for 5 minutes. When the incubation period iscomplete (indicated by the corresponding light 22), the hemoglobincontrol card 42 is placed in card reader 28 and the incubated cuvetteassembly 40 is placed in shuttle carrier 100. The card and card readerproduces an output on line 130-2 which causes the filter drive motor 112to position the 5050 Angstrom filter in the optical path 104 and setsthe gains of log converter 134 and scaling amplifier 152. in addition,switch 140 is set to connect the output of the log converter to theanalog input of the digital voltmeter in response to card reader outputon line 130-7, and switch 150 is set to connect precision voltage source160 to the reference input of the digital voltmeter 142 via scalingamplifier 1S2, switch 154 andstorage circuit 156.

Upon depression of start button 34, logic 162 causes motor 102 toadvance the cuvette assembly 40 from position 1 through position 2 toposition 3. Logic circuit 162 conditions switch 136 to maintain the logconverter circuitry in zeroing mode until position 3 is reached (andchamber 60-2 is positioned in the optical path 104). In this positionthe output of the log converter circuit 134 is A --the absorbance of thematerial in chamber 60-2. The log converter zeroing operation isterminated by an output from sensor 164 via logic 162 to switch 136 asthe cuvette 40 is advanced by shuttle 100 to position the chamber 60-3in optical path 104. The output of the log converter 134 is now thevalue A -A and is applied via switch 140 to the analog input of digitalvoltmeter 142. The strobing pulse is generated by logic 162 on line 176to gate the output value generated by digital voltmeter 142 to digitaldisplay 30, and at the same time the strobing pulse applied to the errorlogic to check whether the scaled precision voltage value is within apreset limit as determined by an output from the card reader on line130-8. As in the other cases, if the output voltage is outside thoselimits lamp 36 is energized. Display 30 displays the digital value ofhemoglobin in grams per 100 milliliters, the digital voltmeter 142having generating the ratio (A A X k/v, the output being an absoluteabsorbance measurement of the sample minus a standard.

Enzyme analyses made in a rate mode. For example, in a determination oflactic dehydrogenase (LDH) by the Wacker method, cuvette assembly 40when received by the technician has a reagent in powder form in chamber60-2 only. Three milliliters of distilled water are added to chamber60-2 to reconstitute the reagent and the materials then mixed byinversion and then incubated at 37C for minutes. When the incubationperiod is complete, 100 milliliters of serum is added to chamber 60-2,the chamber is rescaled and subjected to mixing and then reincubation at37C. The corresponding LDH data card 42 is inserted in card reader 28;filter wheel 108 is rotated to position the 3,400 Angstrom filter in theoptical path 104 in response to an output on line 130-2; logic 162 issignalled that a rate mode of operation is to be performed in responseto an output on line 130-3; the log converter 134 is calibrated inresponse to an output on line 130-4; switch 140 is set to connect theoutput of amplifier 148 to the analog input of digital voltmeter 142 inresponse to an output on line 130-7', switch 150 is set to connectprecision voltage source 160 to the reference input of digital voltmeter142 inresponse to an output on line -5; and the units are set by anout-' put on line 130-9.

In this mode, after the incubated cuvette assembly 40 has been insertedin shuttle 100 upon depression of start button 34, the shuttle isadvanced until chamber 60-2 is positioned in the optical path 104. Atthat point motor 102 is stopped in response to an output from ANDcircuit 380. Timer 390 is released by a signal on line 358 to ANDcircuit 384. The log converter 134 has been ina zeroing mode in responseto a signal applied from AND circuit 386 through OR circuit 414 toswitch 136 and filter network 146 remains reset until time 0011 (switch230 is held closed by a signal online 172). The initial absorbancereading, transformed to voltage, has been established by the zeroingoperation of the log converter circuit 134 which. terminates at time0010 which the output of OR circuit 388 ends. Starting from this point alinearly increasing voltage ramp is monitored over a period of timecontrolled by timer 390. This ramp signal is differentiated bydifferentiator circuit 144 to provide a signal which is passed by filter146 and absolute value amplifier 148 through switch to the analog inputof digital voltmeter 142. At the end of the timing interval (1 1 10),the digital voltmeter is strobed by an output on line 176 to digitallydisplay a reading in international units of the amount of lacticdehydrogenase in the serum. At 11 11 time, the output of AND circuit 404terminates and motor 102 is restarted (the cuvette 40 being promptlyreset at point 334); OR circuit 388 has an output that places logconverter circuit 134 in a zeroing mode again; and AND circuit 392ceases to pass clock pulses. Motor 102 stops in response to a signal atterminal 344.

Thus the invention provides a convenient and versatile system forperforming a variety of chemical analyses and is particularly useful inperformance of analyses of blood and other body fluids. Both modeselection and calibrating information is furnished by a control record.The analysis sequence is automatically performed in any of the modessolely in response to depression of start button 34. No manualadjustments are required. The system is easily operated by untrainedpersonnel and enables analytical information to be made availablequickly, accurately and inexpensively.

While a particular embodiment of the invention has been shown anddescribed, various modifications thereof will be apparent to thoseskilled in theart. For example, the sample chambers may be disposed in aeuvette carrier rather than in one piece unit. Therefore it is notintended that the invention be limited to the dis-- closed embodiment orto details thereof and departures may be made therefrom within thespirit and scope of the invention as defined in the claims.

What is claimed is:

1. An analysis system comprising container structure having a pluralityof chambers, at least one .of which contains a stored chemical material,means for introducing a material to be analyzed into said one chamberfor mixing with said stored chemical material, a record specifyinginformation as to the nature of said stored chemical material and thetype of analysis to be performed, instrumentation for performing ananalysis including means for receiving said container structure, sensorcircuitry adjacent said container structure receiving means forproducing a signal representative of material in the chambers of saidcontainer structure in said container structure receiving means, saidsensor circuitry comprising a radiation source and a detector in spacedrelation defining an optical path, and said container structurereceiving means positioning said container structure in said opticalpath, a first storage circuit responsive to said sensor circuitry forholding a first signal representative of material in'a first chamber, asecond storage circuit for holding a second signal representative ofmaterial in a second chamber as a function of said first signal, andcircuitry for generating a comparison signal as a function of said firstand second stored signals, and means responsive to information on therecord for setting said storage circuits to perform the analysis as afunction of information specified by said record. I

2. The system as claimed in claim 1 and further including circuitry formodifying an output signal produced by said detector as a function ofmaterial in said container structure as a function of another outputsignal produced by said detector to provide a signal indicative of aparameter of the material in said container structure. 7

3. The system as claimed in claim 2 and further including meansresponsive to said record for adjusting said modifying circuitry.

4. The system as claimed in claim 1 wherein said container structureincludes three sample chambers for holding an unknown material to beanalyzed, a standard material, and a blank material, and said secondmeans includes circuitry for generating three signals 8,, S and S twodifference signals (S -S and (8 -5 and said comparison signal is afunction of the ratio-of said two difference signals and indicates acharacteristic of said unknown material.

5. The system as claimed in claim 4 and further including meansresponsive to said record for adjusting said signal generatingcircuitry.

6. An analysis system comprising a radiation source, a radiation sensordisposed in spaced relation from said radiation source, means forpositioning a set of three sample chambers between said radiation sourceand said radiation sensor circuitry for producing a first output signalin response to radiation passing through two chambers of said set ofsample chambers and circuitry for modifying said first output signal asa function of a second output signal produced as a result of radiationpassing through the third chamber of said set of sample chambers forgenerating an output signal that is a function of the ratio of twodifferent signals (S -S and (S2 S3) to provide an indication of acharacteristic of material in one of said sample chambers.

7 The system as claimed in claim 6 wherin' zia modifying circuitryincludes a first storage circuit for storing a signal 8;, representativeof the characteristics of material in a first sample chamber, and switchmeans for controlling the application of signals from said radiationdetector to said first storage circuit.

8.,The system as claimed in claim 6 and further including sequencingmeans for moving said set of sample chambers relative to said radiationpath and wherein said modifying circuitry includes means responsive tosaid sequencing means for controlling the generation of said outputsignal.

9. The system as claimed in claim 6 and further including record sensormeans responsive to a record coordinated with the contents of at leastone of said sample chambers for controlling said modifying circuitry. I1

10. A chemical analysis instrument for use with a euvette carrier havinga plurality of, sample chambers comprising a photometer sectionincluding a radiation source, a radiation detector, a support forpositioning a cuvette carrier in an optical path between said radiationsource and said radiationdetector so that said sample chambers areoperatively disposed in said optical path, signal modifying circuitryresponsive to the output of said radiation detector for generating anoutput signal as a function of material in said sample chambers on theradiation in said optical path, said signal modifying circuitryincluding a logarithmic signal processing circuit, first signal storingcircuitry for storing a first output of said logarithmic signalprocessing circuit as a function of the contents of one sample chamber,second signal storing circuitry for storing a second output of saidlogarithmic signal processing circuit asa.

function of the contents of a second'sample chamber, sequencer means forcontrolling said modifying circuitry as a function of the selectiveoperative disposition of said sample chambers in said optical path tostore a signal in said first signal storing circuitry and to store asignal in said second signal storing circuitry and output circuitry forgenerating a modified signal as a function of said stored signals.

11. The instrument as claimed in claim Y10 and further including a drivefor moving said carrier support relative to said optical path tosequentially position said sample chambers in said optical path.

12. The instrument as claimed in claim 10 and further including a recordsensor responsive to a record correlated with said cuvette carrier foradjusting said signal modifying circuitry as a function of the chemicalanalysis to be performed.

13. The instrument as claimed in claim 12 and further including meansresponsive to said record sensor for performing an analysis of the ratetype and timer means responsive to coding on said cuvette carrier forcontrolling the application of the resulting output signal to saidoutput circuitry.

14. The instrument as claimed in claim 10 and further including anincubator section including interlock means responsive to coding on saidcuvette carrier for providing an incubation control for the chemicalanalysis to be performed.

15. The instrument as claimed in claim 10 and further including a filtermechanism and a record sensor responsive to a record correlated withsaid cuvette carrier for selectively positioning a filter in saidoptical path as a function of the type of chemical analysis to beperformed.

16. The instrument as claimed in claim 10 and further including meansresponsive to a single operation initiating command to cause saidsequencer means to initiate and complete an analysis cycle involving theoperative disposition of said plurality of sample chambers in saidoptical path.

17. The instrument as claimed in claim 10 and further including meansresponsive to an output of said radiation detector for producing anerror signal when the output of said radiation detector deviates from apre-established value by more than a specified amount.

18. The instrument as claimed in claim 10 further including an outputdevice and wherein said signal modifying circuitry includes a referencechannel for applying a first signal to said output device as a functionof the contents of a first sample chamber and a sample channel forapplying a second signal to said output device as a function of thecontents of a second sample chamber.

19. The instrument as claimed in claim 18 wherein said signal modifyingcircuitry further includes a rate channel for applying a third signal tosaid output device as a function of the rate of change of acharacteristic of material in a sample chamber.

20. The instrument as claimed in claim 12 and further including anoutput device and wherein said signal modifying circuitry includes firstand second signal processing channels, each said signal processingchannel including means responsive to said record sensor for adjustingthe gain of the channel, and means for selectively connecting said firstand second channels in circuit between said radiation detector and saidoutput device as a functionof the operation of said sequencer means.

21. The instrument as claimed in claim 20 wherein said signal modifyingcircuitry further includes a third channel having means responsive tothe rate of change of the output of said radiation detector and meansresponsive to said record sensor and said sequencer means foroperatively connecting said third channel in circuit between saidradiation detector and said output device.

22. The instrument as claimed in claim 20 and further including meansresponsive to the output of one of said channels for producing an errorsignal when the output of said one channel deviates from apreestablished value by more than an amount specified by a signal fromsaid record sensor.

23. The instrument as claimed in claim 12 and further including a drivefor moving said carrier support relative to said optical path tosequentially position said sample chambers in said optical path.

24. The instrument as claimed in claim 23 and further including a filtermechanism responsive to said record sensor for selectively positioning afilter in said optical path.

25. A chemical analysis instrument for use with a cuvette carrier havinga plurality of sample chambers comprising a photometer section includinga radiation source, a radiation detector, a support for positioning acuvette carrier in an optical path between said radiation source andsaid radiation detector so that said sample chambers are operativelydisposed in said optical path, signal modifyingcircuitry, responsive tothe output of said radiation detector for generating an output signal asa function of the effect of material in said sample chambers on theradiation in said optical path, an output device, said signal modifyingcircuitry including a reference channel for applying a first signal tosaid output device as a function of the contents of a first samplechamber, a sample channel for applyin a second signal to said outputdevice as a function 0 he contents of a second sample chamber, a ratechannel for applying a third signal to said output device as a functionof the rate of change of a characteristic of material in a samplechamber, detector responsive circuitry for generating an output signalas a logarithmic function of the output of said radiation detector,means for applying said logarithmic function output signalto saidreference, sample, and rate channels, means for storing a logarithmicfunction output signal, means for storing an output signal of saidreference channel, a record sensor responsive to a record correlatedwith said cuvette carrier for adjusting said signal modifying circuitryas a function of the type of chemical analysis to be performed, a filtermechanism responsive to said record sensor for selectively positioning afilter in said optical path, means responsive to said record sensor foradjusting the gains of said logarithmic circuitry and said referencechannel, sequencer means for generating control signals as a function ofthe selective operative disposition of said sample chambers in saidoptical path, and means responsive to said sequencer means forselectively connecting said reference, sample, and rate channels incircuit between said radiation detector and said output device as afunction of the operation of said sequencer means.

26. The instrument 7 as claimed in claim 25 and further including meansresponsive to a single operation initiating command to cause saidsequencer means to initiate and-complete an analysis cycle involving theoperative disposition of said plurality of sample chambers in saidoptical path. 7

27. The instrument as claimed in claim 26 and further including meansresponsive to an output of said radiation detector for producing anerror signal when the output of said radiation detector deviates from apre-established value by more than an amount specified by a signal fromsaid record sensor.

28. The instrument as claimed in claim 25 and further including anincubator section including interlock means responsive to coding on saidcuvette carrier for providing an incubation control for the chemical

1. An analysis system comprising container structure having a pluralityof chambers, at least one of which contains a stored chemical material,means for introducing a material to be analyzed into said one chamberfor mixing with said stored chemical material, a record specifyinginformation as to the nature of said stored chemical material and thetype of analysis to be performed, instrumentation for performing ananalysis including means for receiving said container structure, sensorcircuitry adjacent said container structure receiving means forproducing a signal representative of material in the chambers of saidcontainer structure in said container structure receiving means, saidsensor circuitry comprising a radiation source and a detector in spacedrelation defining an optical path, and said container structurereceiving means positioning said container structure in said opticalpath, a first storage circuit responsive to said sensor circuitry forholding a first signal representative of material in a first chamber, asecond storage circuit for holding a second signal representative ofmaterial in a second chamber as a function of said first signal, andcircuitry for generating a comparison signal as a function of said firstand second stored signals, and means responsive to information on therecord for setting said storage circuits to perform the analysis as afunction of information specified by said record.
 1. An analysis systemcomprising container structure having a plurality of chambers, at leastone of which contains a stored chemical material, means for introducinga material to be analyzed into said one chamber for mixing with saidstored chemical material, a record specifying information as to thenature of said stored chemical material and the type of analysis to beperformed, instrumentation for performing an analysis including meansfor receiving said container structure, sensor circuitry adjacent saidcontainer structure receiving means for producing a signalrepresentative of material in the chambers of said container structurein said container structure receiving means, said sensor circuitrycomprising a radiation source and a detector in spaced relation definingan optical path, and said container structure receiving meanspositioning said container structure in said optical path, a firststorage circuit responsive to said sensor circuitry for holding a firstsignal representative of material in a first chamber, a second storagecircuit for holding a second signal representative of material in asecond chamber as a function of said first signal, and circuitry forgenerating a comparison signal as a function of said first and secondstored signals, and means responsive to information on the record forsetting said storage circuits to perform the analysis as a function ofinformation specified by said record.
 2. The system as claimed in claim1 and further including circuitry for modifying an output signalproduced by said detector as a function of material in said containerstructure as a function oF another output signal produced by saiddetector to provide a signal indicative of a parameter of the materialin said container structure.
 3. The system as claimed in claim 2 andfurther including means responsive to said record for adjusting saidmodifying circuitry.
 4. The system as claimed in claim 1 wherein saidcontainer structure includes three sample chambers for holding anunknown material to be analyzed, a standard material, and a blankmaterial, and said second means includes circuitry for generating threesignals S1, S2, and S3, two difference signals (S1-S3) and (S2-S3), andsaid comparison signal is a function of the ratio of said two differencesignals and indicates a characteristic of said unknown material.
 5. Thesystem as claimed in claim 4 and further including means responsive tosaid record for adjusting said signal generating circuitry.
 6. Ananalysis system comprising a radiation source, a radiation sensordisposed in spaced relation from said radiation source, means forpositioning a set of three sample chambers between said radiation sourceand said radiation sensor circuitry for producing a first output signalin response to radiation passing through two chambers of said set ofsample chambers and circuitry for modifying said first output signal asa function of a second output signal produced as a result of radiationpassing through the third chamber of said set of sample chambers forgenerating an output signal that is a function of the ratio of twodifferent signals (S1-S3) and (S2-S3) to provide an indication of acharacteristic of material in one of said sample chambers.
 7. The systemas claimed in claim 6 wherein said modifying circuitry includes a firststorage circuit for storing a signal S3 representative of thecharacteristics of material in a first sample chamber, and switch meansfor controlling the application of signals from said radiation detectorto said first storage circuit.
 8. The system as claimed in claim 6 andfurther including sequencing means for moving said set of samplechambers relative to said radiation path and wherein said modifyingcircuitry includes means responsive to said sequencing means forcontrolling the generation of said output signal.
 9. The system asclaimed in claim 6 and further including record sensor means responsiveto a record coordinated with the contents of at least one of said samplechambers for controlling said modifying circuitry.
 10. A chemicalanalysis instrument for use with a cuvette carrier having a plurality ofsample chambers comprising a photometer section including a radiationsource, a radiation detector, a support for positioning a cuvettecarrier in an optical path between said radiation source and saidradiation detector so that said sample chambers are operatively disposedin said optical path, signal modifying circuitry responsive to theoutput of said radiation detector for generating an output signal as afunction of material in said sample chambers on the radiation in saidoptical path, said signal modifying circuitry including a logarithmicsignal processing circuit, first signal storing circuitry for storing afirst output of said logarithmic signal processing circuit as a functionof the contents of one sample chamber, second signal storing circuitryfor storing a second output of said logarithmic signal processingcircuit as a function of the contents of a second sample chamber,sequencer means for controlling said modifying circuitry as a functionof the selective operative disposition of said sample chambers in saidoptical path to store a signal in said first signal storing circuitryand to store a signal in said second signal storing circuitry and outputcircuitry for generating a modified signal as a function of said storedsignals.
 11. The instrument as claimed in claim 10 and further includinga drive for moving said carrier support relative to said optical path tosequentially position said sample chambers in said optical path.
 12. Theinstrument as claimed in claim 10 and further including a record sensorresponsive to a record correlated with said cuvette carrier foradjusting said signal modifying circuitry as a function of the chemicalanalysis to be performed.
 13. The instrument as claimed in claim 12 andfurther including means responsive to said record sensor for performingan analysis of the rate type and timer means responsive to coding onsaid cuvette carrier for controlling the application of the resultingoutput signal to said output circuitry.
 14. The instrument as claimed inclaim 10 and further including an incubator section including interlockmeans responsive to coding on said cuvette carrier for providing anincubation control for the chemical analysis to be performed.
 15. Theinstrument as claimed in claim 10 and further including a filtermechanism and a record sensor responsive to a record correlated withsaid cuvette carrier for selectively positioning a filter in saidoptical path as a function of the type of chemical analysis to beperformed.
 16. The instrument as claim in claim 10 and further includingmeans responsive to a single operation initiating command to cause saidsequencer means to initiate and complete an analysis cycle involving theoperative disposition of said plurality of sample chambers in saidoptical path.
 17. The instrument as claimed in claim 10 and furtherincluding means responsive to an output of said radiation detector forproducing an error signal when the output of said radiation detectordeviates from a pre-established value by more than a specified amount.18. The instrument as claimed in claim 10 further including an outputdevice and wherein said signal modifying circuitry includes a referencechannel for applying a first signal to said output device as a functionof the contents of a first sample chamber and a sample channel forapplying a second signal to said output device as a function of thecontents of a second sample chamber.
 19. The instrument as claimed inclaim 18 wherein said signal modifying circuitry further includes a ratechannel for applying a third signal to said output device as a functionof the rate of change of a characteristic of material in a samplechamber.
 20. The instrument as claimed in claim 12 and further includingan output device and wherein said signal modifying circuitry includesfirst and second signal processing channels, each said signal processingchannel including means responsive to said record sensor for adjustingthe gain of the channel, and means for selectively connecting said firstand second channels in circuit between said radiation detector and saidoutput device as a function of the operation of said sequencer means.21. The instrument as claimed in claim 20 wherein said signal modifyingcircuitry further includes a third channel having means responsive tothe rate of change of the output of said radiation detector and meansresponsive to said record sensor and said sequencer means foroperatively connecting said third channel in circuit between saidradiation detector and said output device.
 22. The instrument as claimedin claim 20 and further including means responsive to the output of oneof said channels for producing an error signal when the output of saidone channel deviates from a pre-established value by more than an amountspecified by a signal from said record sensor.
 23. The instrument asclaimed in claim 12 and further including a drive for moving saidcarrier support relative to said optical path to sequentially positionsaid sample chambers in said optical path.
 24. The instrument as claimedin claim 23 and further including a filter mechanism responsive to saidrecord sensor for selectively positioning a filter in said optical path.25. A chemical analysis instrument for use with a cuvette carrier havinga plurality of sample chambers Comprising a photometer section includinga radiation source, a radiation detector, a support for positioning acuvette carrier in an optical path between said radiation source andsaid radiation detector so that said sample chambers are operativelydisposed in said optical path, signal modifying circuitry responsive tothe output of said radiation detector for generating an output signal asa function of the effect of material in said sample chambers on theradiation in said optical path, an output device, said signal modifyingcircuitry including a reference channel for applying a first signal tosaid output device as a function of the contents of a first samplechamber, a sample channel for applying a second signal to said outputdevice as a function of the contents of a second sample chamber, a ratechannel for applying a third signal to said output device as a functionof the rate of change of a characteristic of material in a samplechamber, detector responsive circuitry for generating an output signalas a logarithmic function of the output of said radiation detector,means for applying said logarithmic function output signal to saidreference, sample, and rate channels, means for storing a logarithmicfunction output signal, means for storing an output signal of saidreference channel, a record sensor responsive to a record correlatedwith said cuvette carrier for adjusting said signal modifying circuitryas a function of the type of chemical analysis to be performed, a filtermechanism responsive to said record sensor for selectively positioning afilter in said optical path, means responsive to said record sensor foradjusting the gains of said logarithmic circuitry and said referencechannel, sequencer means for generating control signals as a function ofthe selective operative disposition of said sample chambers in saidoptical path, and means responsive to said sequencer means forselectively connecting said reference, sample, and rate channels incircuit between said radiation detector and said output device as afunction of the operation of said sequencer means.
 26. The instrument asclaimed in claim 25 and further including means responsive to a singleoperation initiating command to cause said sequencer means to initiateand complete an analysis cycle involving the operative disposition ofsaid plurality of sample chambers in said optical path.
 27. Theinstrument as claimed in claim 26 and further including means responsiveto an output of said radiation detector for producing an error signalwhen the output of said radiation detector deviates from apre-established value by more than an amount specified by a signal fromsaid record sensor.
 28. The instrument as claimed in claim 25 andfurther including an incubator section including interlock meansresponsive to coding on said cuvette carrier for providing an incubationcontrol for the chemical analysis to be performed.